Synthetic resin process and article useful for plating applications

ABSTRACT

A method for processing reinforcing filler-filled synthetic resins and applications made therefrom wherein the resulting articles have the ability to be plated to form a structurally aesthetic product substantially free of visual defects. The process utilizes an accelerated heat and cool process to form a resin-rich surface that is substantially free of any reinforcing fillers, such as fiber strands and/or bundles, on the external surface of the article. As such, the resulting article is capable of being plated to form an article that is substantially free of visual defects caused by these fillers on the surface of the article.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.12/297,512, filed Jan. 21, 2009, which is a 371 filing of InternationalApplication Serial No. PCT/US2008/075890, filed Sep. 10, 2008, whichclaims priority to U.S. Provisional Application Ser. No. 60/971,080,filed Sep. 10, 2007, and U.S. Provisional Application Ser. No.60/971,295, filed Sep. 11, 2007, all of which are hereby incorporated byreference in their entirety.

FIELD OF INVENTION

The present invention relates to synthetic resin processes and articlesmade therefrom and, in particular, for synthetic resin processes andarticles made therefrom that have use in plating applications.

BACKGROUND OF INVENTION

Many companies are replacing metal parts with alternative materials thatare lighter in weight but that are also capable of maintaining thestructural benefits of metal. Due to the greater ease in processingplastic material into selected shapes, plastic materials have increasedin popularity in terms of replacing metal parts. However, in manyinstances, plastic alone cannot match the strength properties of metals.As such, reinforced plastics or plastic composites have been utilized.Specifically, plastic composites include a reinforcing fiber in apolymer matrix. In many instances, the reinforcing fiber is glass fiber,although high-strength fibers such as aramid and carbon have been usedin other applications.

The use of high glass loadings in thermoplastic materials tends toincrease stiffness (tensile and flexural modulus) and strength (tensile& flexural strength) of the reinforced plastic. However, the use ofhighly glass filled materials has a negative effect on the surfacequality and aesthetics of molded parts. After molding, the glass fiberson the exterior surface of the part produce a dull or matted finish andthese fibers interfere with the adhesion of a subsequent painting orplating application that otherwise would cover the fibers.

Other types of filled or reinforced plastic materials suffer fromsimilar problems. Traditional “high modulus” materials contain glass, ormica, or other fillers that are capable of increasing the modulus, orstiffness, of the material. Examples include glass filled PBT, PA,PC/ABS, PP, etc. However, the addition of fillers also has an adverseeffect on the surface quality of the part. Therefore, these types ofmaterials are molded in low gloss, textured applications. These partscan also be painted, but a primer is typically needed to cover thesurface imperfections prior to the top-coat paint layer. As a result,“aesthetic” materials are typically unfilled, amorphous resins that canbe easily molded-in-color, painted or metal plated. These materialsinclude unfilled ASA, ABS, PC/ABS, PPO, etc. Again, however, thesematerials do not provide the structural strength necessary for manymetal replacement applications.

Accordingly, it would be beneficial to provide a process for moldingfiber-reinforced thermoplastic resins to produce an article having aresin-rich surface such that the presence of glass fibers and/or bundleson the external surface of the article are substantially eliminated. Itwould also be beneficial to provide a process for moldingfiber-reinforced thermoplastic resins to produce an article capable ofbeing plated. It would also be beneficial to provide an article moldedfrom a fiber-reinforced thermoplastic resin wherein the resultingarticle were capable of being plated with a surface substantially freeof visual defects.

SUMMARY OF THE INVENTION

The present invention provides a method for processing reinforcingfiller-filled synthetic resins and applications made therefrom whereinthe resulting articles have the ability to be plated to form astructurally aesthetic product that is substantially free of visualdefects. The process utilizes an accelerated heat and cool process toform a resin-rich surface that is substantially free of any reinforcingfillers, such as fiber strands and/or bundles, on the external surfaceof the article. As such, the resulting article is capable of beingplated to form an article that is substantially free of visual defectscaused by these fillers on the surface of the article. The moldedarticle is beneficially applicable in structural aesthetic applicationswherein the surface quality of the molded article is important.

Accordingly, in one aspect, the present invention provides a process formolding an article including the steps of injecting a thermoplasticresin having a reinforcing filler into a mold to contact a mold surface,wherein the mold has at least one channel for receiving a temperaturecontrol fluid; supplying a heated temperature control fluid to rapidlyheat the mold surface to a temperature above the heat deformationtemperature of the thermoplastic resin; molding the thermoplastic resinto form a molded article; and supplying a cooled temperature controlfluid to the mold to rapidly cool the molded article; wherein the moldedarticle is capable of being plated such that at least a portion ofsurface of the molded article is substantially free of any reinforcingfillers.

In another embodiment, a process for molding an article comprises:injecting a thermoplastic resin having a reinforcing filler into a moldsuch that the thermoplastic resin contacts a mold surface, molding thethermoplastic resin to form a molded article; and supplying a cooledtemperature control fluid to the mold to cool the molded article. Thereinforcing filler is present in an amount of about 5 wt % to about 70wt %, based upon a total weight of the thermoplastic resin with thereinforcing filler. The mold surface has a temperature greater than aheat deformation temperature of the thermoplastic, wherein the mold hasat least one channel for receiving a temperature control fluid. Themolded article has a gloss rating of greater than or equal to 40, asmeasured with a 60° gloss meter.

In another aspect, the present invention provides a thermoplastic resinincluding a reinforcement filler, wherein the molded article is capableof being plated such that at least a portion of surface of the moldedarticle is substantially free of individual fillers or bundles offillers.

BRIEF DECRIPTION OF THE DRAWINGS

The various embodiments of the present invention can be understood withreference to the following drawings. The components are not necessarilyto scale. Also, in the drawings, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is a graph showing the temperatures of conventional moldingtechnologies as compared to the molding temperatures of the processes ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the followingdescription and examples that are intended to be illustrative only sincenumerous modifications and variations therein will be apparent to thoseskilled in the art. As used in the specification and in the claims, theterm “comprising” may include the embodiments “consisting of” and“consisting essentially of.” All ranges disclosed herein are inclusiveof the endpoints and are independently combinable. The endpoints of theranges and any values disclosed herein are not limited to the preciserange or value; they are sufficiently imprecise to include valuesapproximating these ranges and/or values. Reference throughout thespecification to “one embodiment”, “another embodiment”, “anembodiment”, and so forth, means that a particular element (e.g.,feature, structure, and/or characteristic) described in connection withthe embodiment is included in at least one embodiment described herein,and can or can not be present in other embodiments. In addition, it isto be understood that the described elements can be combined in anysuitable manner in the various embodiments and are not limited to thespecific combination in which they are discussed.

As used herein, approximating language may be applied to modify anyquantitative representation that may vary without resulting in a changein the basic function to which it is related. Accordingly, a valuemodified by a term or terms, such as “about” and “substantially,” maynot be limited to the precise value specified, in some cases. In atleast some instances, the approximating language may correspond to theprecision of an instrument for measuring the value.

It is known that when molding a material for an aesthetic application,like a metal-plated or high gloss part, that increasing tool temperatureimproves the surface quality of the part. In general, by operating at aslightly higher molding temperature, a more resin-rich surface (i.e.substantially free of impurities) helps to reduce molded in stress,provides a resin rich surface, and allows improved tool surfacereplication. However, simply operating at a slightly increasedtemperature does not provide a resin-rich surface when the thermoplasticresin includes a filler, such as a fiber filler.

Conversely, when a thermoplastic resin is molded by an injection moldingor compression molding, in order to avoid elongation of time in amolding cycle due to change in temperature of the mold, molding iscarried out at a marginal temperature range which barely permits themelt to be filled into the mold and the product taken out from the moldwithout deformation. As such, the higher temperatures needed to helpprovide a resin-rich surface end up resulting in a longer molding time,thereby increasing the overall cycle time and reducing the productivity.

Accordingly, the present invention utilizes a heat and cool technologywhereby the molding process is operated at a higher molding temperature,and one higher than normally utilized for filled resins, but that offersreduced cycle times. This is accomplished by utilizing a heatedtemperature control fluid to rapidly (e.g., heat at a rate of 0.1 to500° C. per minute) heat the mold followed by the use of a cooledtemperature fluid control fluid to rapidly cool the molded part. As aresult, cycle times are reduced while permitting a resin-rich surface tobe formed that is substantially free of fillers, such as fibers or fiberbundles, on at least a portion of the exterior surface of the moldedpart. Since the presence of impurities on the surface of a part, such asfibers and fiber bundles, interfere with subsequent plating processes,the molded articles made by the present invention are also capable ofbeing plated (e.g., chrome plated). As used herein, “capable of beingplated” refers to a molded part that is substantially free of anyfillers on the portion of the surface to be plated. A molded part thatis capable of being plated is one that is substantially free of anyvisual defects on the plated portion of the molded part. Visual defectsinclude voids and blisters.

In addition, when a thermoplastic resin is subjected to injectionmolding, if the temperature of the mold is kept at a high temperatureupon filling the melt into the mold, since the fluidity of the resin isimproved, it becomes possible to take an advantage in forming theproduct into a thin-walled product as well as in improving replicationproperty, i.e., how well the shape of the cavity surface is replicatedto the surface of the product. In addition, a weld line becomes notconspicuous. As such, the concepts of the present invention can also beutilized to form thin-walled parts capable of being plated.

Accordingly, the present invention provides a method for processingreinforcing filler-filled synthetic resins and applications madetherefrom wherein the resulting articles have the ability to be platedto form a structurally aesthetic product that is substantially free ofvisual defects. The process utilizes an accelerated heat and coolprocess to form a resin-rich surface that is substantially free of anyreinforcing fillers, such as fiber strands and/or bundles, on theportion of the external surface of the article to be plated. As such,the resulting article is capable of being plated to form an article thatis substantially free of visual defects, such as voids and blisters,caused by these fillers on the surface of the article. The moldedarticle is beneficially applicable in structural aesthetic applicationswherein the surface quality of the molded article is important.

The present invention utilizes a heat and cool process technology tohelp provide a resin-rich surface while also providing lower cycletimes. In this process, the injection mold (tool) is heated with aheated temperature control fluid, such as pressurized water, such thatthe mold temperature is heated to a temperature well above traditionalinjection molding temperatures (and above the HDT of the material).After molding, the tool is subsequently cooled to provide a resin richsurface on the molded part.

Accordingly, in a first aspect, the present invention provides a methodof processing a synthetic resin to form a molded article capable ofbeing plated. Accordingly, the molded article is constructed from athermoplastic resin capable of being injected molded. In one embodiment,the thermoplastic resin may be selected from a wide variety ofthermoplastic resins, blend of thermoplastic resins, thermosettingresins, or blends of thermoplastic resins with thermosetting resins. Thethermoplastic resin may also be a blend of polymers, copolymers,terpolymers, or combinations including at least one of the foregoingthermoplastic resins. Examples of the thermoplastic resin include, butare not limited to, polyacetals, polyacrylics, polycarbonates,polystyrenes, polyesters, polyamides, polyamideimides, polyarylates,polyarylsulfones, polyethersulfones, polyphenylene sulfides, polyvinylchlorides, polysulfones, polyimides, polyetherimides,polytetrafluoroethylenes, polyetherketones, polyether etherketones,polyether ketone ketones, polybenzoxazoles, polyoxadiazoles,polybenzothiazinophenothiazines, polybenzothiazoles,polypyrazinoquinoxalines, polypyromellitimides, polyquinoxalines,polybenzimidazoles, polyoxindoles, polyoxoisoindolines,polydioxoisoindolines, polytriazines, polypyridazines, polypiperazines,polypyridines, polypiperidines, polytriazoles, polypyrazoles,polypyrrolidines, polycarboranes, polyoxabicyclononanes,polydibenzofurans, polyphthalides, polyacetals, polyanhydrides,polyvinyl ethers, polyvinyl thioethers, polyvinyl alcohols, polyvinylketones, polyvinyl halides, polyvinyl nitriles, polyvinyl esters,polysulfonates, polysulfides, polythioesters, polysulfones,polysulfonamides, polyureas, polyphosphazenes, polysilazanes, or thelike, or a combination including at least one of the foregoingthermoplastic resins.

Specific non-limiting examples of blends of thermoplastic resins includeacrylonitrile-butadiene-styrene/nylon,polycarbonate/acrylonitrile-butadiene-styrene, polyphenyleneether/polystyrene, polyphenylene ether/polyamide,polycarbonate/polyester, polyphenylene ether/polyolefin, andcombinations including at least one of the foregoing blends ofthermoplastic resins.

Examples of thermosetting resins include polyurethane, natural rubber,synthetic rubber, epoxy, phenolic, polyesters, polyamides, silicones,and mixtures including any one of the foregoing thermosetting resins.Blends of thermoset resins as well as blends of thermoplastic resinswith thermosets can be utilized.

Exemplary examples of the thermoplastics resin include organic polymersthat are flexible at temperatures of about 200° C. to about −60° C.Examples of beneficial thermoplastic resins that may be used in thepresent invention include, but are not limited to,acrylonitrile-butadiene-styrene (ABS), polycarbonate, polycarbonate/ABSblend, a copolycarbonate-polyester, acrylic-styrene-acrylonitrile (ASA),acrylonitrile-(ethylene-polypropylene diamine modified)-styrene (AES),phenylene ether resins, glass filled blends of polyphenylene oxide andpolystyrene, blends of polyphenylene ether/polyamide, blends ofpolycarbonate/PET/PBT, polybutylene terephthalate and impact modifier,polyamides, phenylene sulfide resins, polyvinyl chloride PVC, highimpact polystyrene (HIPS), low/high density polyethylene, polypropyleneand thermoplastic olefins (TPO), polyethylene and fiber composites, andpolypropylene and fiber composites.

In addition to the thermoplastic resin, the reinforcing filler-filledthermoplastic materials used in the present invention include aplurality of reinforcing fillers, such as fibers fillers. The conceptsof the present invention can be utilized with a variety of fiber-filledthermoplastic materials, depending on the selected characteristics ofthe fiber-filled thermoplastic material and any article molded from thefiber-filled thermoplastic material. For example, in one embodiment, thefiber is a glass fiber used for reinforcement. In an alternativeembodiment, the fiber-filled thermoplastic material includes carbonfibers to impart improved conductivity to the fiber-filled thermoplasticmaterials and any article made therefrom. In another embodiment, thefiber-filled thermoplastic material may include aramid fibers. Otherfibers that may be used include metal fibers, metal-coated fibers,organic fibers, ceramic fibers, biocompatible fibers or any other fibercapable of withstanding the process to impart the selectedcharacteristic to the molded article. In alternative embodiments,non-fiber fillers may be used for the reinforcing fillers, such as glassbeads, glass flakes, talc, clay or any other reinforcement filler. Inthe various embodiments, the reinforcing filler can be present in thereinforcing filler-filled thermoplastic material in an amount of lessthan or equal to about 70 weight percent (wt %), specifically, about 1wt % to about 70 wt %, more specifically, about 5 wt % to about 40 wt %,even more specifically, about 10 wt % to about 30 wt %, wherein theweight is based upon a total weight of the reinforcing filler-filledthermoplastic material.

In use, the processes of the present invention utilize heat and coolprocess technology to heat the tool above the heat distortiontemperature (HDT) of the thermoplastic resin. The fiber-filled resin isthen injected to the mold to form the molded part. Then, cooling themold tool cools the molded part. After the parts have solidified, theyare ejected from the tool cavity. The heating and cooling processes arecontrolled using a temperature control fluid. For heating, a heatedtemperature control fluid is used. For cooling, a cooled temperaturecontrol fluid is utilized. In one embodiment, the temperature controlfluid is pressurized water, with the temperature of the water beingadjusted such that it helps to rapidly heat or cool the mold. In anotherembodiment, the temperature control fluid is unpressurized water, withthe temperature of the water being adjusted such that it helps torapidly heat or cool the mold. In other alternative embodiments, othertemperature control fluids may be used including, but not limited to,steam, oil, or any other non-Freon based temperature control fluid maybe used.

As may be seen in FIG. 1, the processes of the present invention operateon a much higher molding temperature as compared to prior art processes.In the prior art, the molding temperature is typically less than the HDTof the thermoplastic resin. Conversely, the methods of the presentinvention heat the mold surface to be contacted by the thermoplasticresin to a temperature above the heat deformation temperature (HDT) ofthe thermoplastic resin being molded, e.g., greater than 1° C. above theHDT, specifically, 1 to 100° C. above the HDT, more specifically, 15 to100° C. above the HDT, even more specifically, 30 to 100° C. above theHDT, and yet more specifically, 60 to 100° C. above the HDT.

As a temperature control fluid is used, the mold itself is designed tobe capable of using a temperature control fluid. In one embodiment, themold tool includes one or more channels through which both the heatedtemperature control fluid and the cooled temperature control fluid arepassed. In an alternative embodiment, the mold tool includes separatechannels, one for the temperature control fluid and one for the cooledtemperature control fluid. The channels used in the mold tool can be, inone embodiment, traditional (straight) lines, or they can be, in analternative embodiment, conformal (i.e. conforming to the shape of thepart), or they can be flood cooling (where large areas of tool steal areremoved for the water to flow through).

As mentioned above, in alternative embodiments, several different typesof cooling lines can be used. In one beneficial embodiment, conformalcooling is utilized since it permits the rapid heat transfer from themetal used to form the mold tool to the temperature control fluid lines.

As discussed, the processes of the present invention help form moldedparts that are capable of being plated. As discussed, “capable of beingplated” refers to a molded part that is substantially free of any fibersor fiber bundles on the portion of the surface of the molded part to beplated. As such, the molded parts of the present invention can be platedsuch that the resulting plated part is substantially free of any visualdefects, such as voids and blisters, in the plated portion of the part.The molded parts capable of being plated may be plated using any knownplating technology capable of applying a metal or metal-containingcoating to a plastic part. Examples of metals that can be platedinclude, but are not limited to, cadmium, copper, electrolytic andelectroless nickel, gold, silver, tin, zinc plating, or a combinationincluding at least one of the foregoing metals. Examples of platingprocesses that can be used include, but are not limited to, electrolyticplating, electroless plating, anodized plating, physical vapordeposition (PVD) plating, or a combination including at least one of theforegoing plating processes.

The concepts of the present invention can be used to form a variety ofstructurally aesthetic parts including, but not limited to, TV bezels,instrument panel center bezels, automotive parts, such as roof racks,and the like.

The following examples serve to illustrate the invention but are notintended to limit the scope of the invention.

EXAMPLES

In these examples, a polycarbonate/acrylonitrile butadiene styrene(PC/ABS) resin having 20% glass fiber was molded in an injection moldinghigh polish tool having a SPI A2 tool surface. The fiber-filled PC/ABSwas molded using a conventional molding process (the mold temperaturewas not above the HDT of the PC/ABS) and was then molded in a processaccording to the concepts of the present invention wherein thetemperature of the mold was heated to a temperature above the HDT of thePC/ABS using pressurized heated water. The mold was cooled also usingwater as the cooled temperature control fluid. Gloss measurements werethen taken using a 60° gloss meter, and the results recorded in Table 1

TABLE 1 60° Gloss readings on PC/ABS resin molded in a high polish tool(SPI A2 Tool Surface) Conventional Conventional Heat and Cool Heat andCool SPI B2 Tool SPI A2 Tool SPI B2 Tool SPI A2 Tool Sample SurfaceSurface Surface Surface 1 6.8 21.7 3.8 90.6 2 6.3 20.8 3.4 91.7 3 4.211.5 4.0 90.3 4 10.6 16.0 3.5 88.1 5 5.3 17.4 3.3 91.1 Average 6.6 17.53.6 90.4

A2 is a highly polished surface. B2 is a dull, or matte, finish. Heatand Cool replicates the tool surface very well as can be seen in thematte finish replication, whereas the parts made using the polishedsurface had a much higher gloss rating, thereby showing the resin-richsurface as well as the substantial reduction of glass fibers and/orglass bundles on the exterior surface of the molded parts in eithermatte or polished parts. The reinforcing filler-filled articles had agloss rating of greater than or equal to 40, specifically, greater thanor equal to 60, more specifically, greater than or equal to 80, and evenmore specifically, greater than or equal to 90. As a result, the moldedparts made according to the concepts of the present invention arecapable of being subsequently plated.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims All citations referred herein areexpressly incorporated herein by reference.

1. A molded article comprising: a thermoplastic resin including areinforcement filler; wherein the molded article is capable of beingplated such that at least a portion of surface of the molded article issubstantially free of individual fillers or bundles of fillers.
 2. Themolded article of claim 1, wherein the thermoplastic resin is selectedfrom polyacetals, polyacrylics, polycarbonates, polystyrenes,polyesters, polyamides, polyamideimides, polyarylates, polyarylsulfones,polyethersulfones, polyphenylene sulfides, polyvinyl chlorides,polysulfones, polyimides, polyetherimides, polytetrafluoroethylenes,polyetherketones, polyether etherketones, polyether ketone ketones,polybenzoxazoles, polyoxadiazoles, polybenzothiazinophenothiazines,polybenzothiazoles, polypyrazinoquinoxalines, polypyromellitimides,polyquinoxalines, polybenzimidazoles, polyoxindoles,polyoxoisoindolines, polydioxoisoindolines, polytriazines,polypyridazines, polypiperazines, polypyridines, polypiperidines,polytriazoles, polypyrazoles, polypyrrolidines, polycarboranes,polyoxabicyclononanes, polydibenzofurans, polyphthalides, polyacetals,polyanhydrides, polyvinyl ethers, polyvinyl thioethers, polyvinylalcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles,polyvinyl esters, polysulfonates, polysulfides, polythioesters,polysulfones, polysulfonamides, polyureas, polyphosphazenes,polysilazanes, or a combination including at least one of the foregoingthermoplastic resins.
 3. The molded article of claim 1, wherein thethermoplastic resin is selected from acrylonitrile-butadiene-styrene(ABS), polycarbonate, polycarbonate/ABS blend, acopolycarbonate-polyester, acrylic-styrene-acrylonitrile (ASA),acrylonitrile-(ethylene-polypropylene diamine modified)-styrene (AES),phenylene ether resins, glass filled blends of polyphenylene oxide andpolystyrene, blends of polyphenylene ether/polyamide, blends ofpolycarbonate/PET/PBT, polybutylene terephthalate and impact modifier,polyamides, phenylene sulfide resins, polyvinyl chloride PVC, highimpact polystyrene (HIPS), low/high density polyethylene, polypropyleneand thermoplastic olefins (TPO), polyethylene and fiber composites,polypropylene and fiber composites, or a combination thereof.
 4. Themolded article of claim 1, wherein the reinforcing filler is a fiber andthe fiber is selected from glass fiber, ceramic fiber, carbon fiber,aramid fiber, or a combination including at least one of the foregoingfibers.
 5. The molded article of claim 1, wherein the reinforcing filleris present in an amount of about 10 wt % to about 30 wt %, based upon atotal weight of the thermoplastic resin with the reinforcing filler. 6.The molded article of claim 5, wherein the reinforcing filler comprisesglass fiber.
 7. The molded article of claim 6, wherein the thermoplasticresin comprises a polycarbonate/ABS blend.
 8. The molded article ofclaim 1, further comprising chrome plating.
 9. The molded article ofclaim 1, wherein the thermoplastic resin comprises a polycarbonate/ABSblend.
 10. A molded article comprising: a thermoplastic resin includinga reinforcement filler; wherein the molded article is formed byinjecting a thermoplastic resin having a reinforcing filler into a moldto contact a mold surface; supplying a heated temperature control fluidto heat the mold surface to a temperature from 1 to 100° C. above theheat deformation temperature of the thermoplastic resin at a rategreater than 120° C. per minute and less than or equal to 500° C. perminute; molding the thermoplastic resin to form the molded article; andsupplying a cooled temperature control fluid to the mold to cool themolded article.
 11. The molded article of claim 10, wherein the moldedarticle is capable of being plated such that at least a portion of thesurface of the molded article is substantially free of any reinforcingfillers.